It is a well recognized fact that many urban centers have grave difficulties in disposing of human and industrial wastes such as sewage and garbage. These waste products are generally contaminated with bacteria, chemicals, and toxic materials, and are therefore deemed suitable only for disposal. Yet both sewage and garbage contain a wealth of reclaimable materials, as well as a high concentration of biological nutrients. Generally speaking, these potentially useful materials are not reclaimed, due to the difficulty and cost of separating them from the contaminants.
Thus, these waste products are disposed of by land-fill techniques or incineration, in the case of garbage, and by dumping the sewage into estuaries and large bodies of water. Sewage is often given primary and secondary treatment to remove the most dangerous contaminants, in an attempt to reduce the pollution of existing water resources to acceptable levels. Experience has shown, however, that current treatment methods cannot generally economically cope with the increasing volume of sewage, nor with the newer contaminants, e.g., heavy metals, pesticides, phosphates, and the like, contained therein. Likewise, garbage land-fill locations near urban centers are becoming scarce. An ecological crisis seems imminent.
Another waste product disposal problem of little general knowledge, but of great importance, involves the dredging of deep-water harbors and estuaries to maintain ship channels. Millions of cubic yards of material are dredged annually and must be disposed of in a manner compatible with the surrounding environment. Often these dredging spoils are highly saline, and cannot be dumped on land without the risk of contaminating the ground water. Dumping the spoils in the shallows and shoals of bays and estuaries can create such turbidity as to threaten the local fish, waterfowl, and wildlife. It has been proposed to transport these spoils to deep ocean locations for dumping, a method which is economically unfeasible for so large a volume of material, and which also results in the loss of this material which could otherwise be put to practical agricultural usage.